### time dilation

(relativity's ability to make time differ for different objects)

**Time dilation** is the effect that for some
objects, less time as passed than for others,
depending their position and velocity.
It is a consequence of relativity.
**Special relativity** implies time dilation based
upon the relative motion of two objects.
General relativity also produces time dilation
(**gravitational time dilation**)
for objects deeper within a gravitational well compared to
those not so deep within it.
Time dilation challenges intuition based
upon daily experience, but is not only proven,
but some technology that depends upon high-precision
time measurement, such as **GPS**,
requires time dilation to be taken into account
in order to function.
It is not illusion: two accurate clocks go out of
sync if one of them is moved away, then back to the other.

Cosmological time dilation is the apparent
time dilation of events viewed from
large (high redshift) distances.

(*physics,relativity*)
**Further reading:**

http://en.wikipedia.org/wiki/Time_dilation

**Referenced by pages:**

cosmological time dilation

radial velocity (RV)

tired light

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